Development and validation of an HPLC – method for quality control of Pueraria lobata Willd. flower plant material

Pueraria lobata (Willd.) Ohwi (Fabaceae) is a medicinal plant widely used in the traditional Chinese medicine. Pueraria isoflavones are currently a significant target in the pharmaceutical and nutritional research owing to their numerous health promoting properties. Many commercial preparations of isoflavone extracts from the root of the plant are sold as dietary supplements. Nowadays research is more and more focused on the flower of P. lobata and its isoflavone constituents. The efficacy and the safety of such phytopreparations depend on the actual content of active compounds, which is directly linked to the quality of the raw material used for the production. This fact indicates the need for improved quality control.

In this study the development, optimisation and validation of an HPLC – method suitable for Quality Control of Pueraria flower plant material is presented. This analytical method for quantification of the isoflavones: (1) Tectorigenin-7-O-[β-D-xylopyranosyl-(1–6)-β-D-glucopyranoside]; (2) Tectorigenin-7-O-β-D- glucopyranoside and (3) Tectorigenin, was fully validated according to the ICH guidelines in terms of linearity, precision and accuracy. The extraction procedure, the extraction solvent, the extraction yields and the HPLC-conditions were evaluated and optimised. The samples were analysed on a RP C18 column gradiently eluted with a two-phase system consisting of formic acid, water and methanol; detection was at 262 nm. The isoflavons identified in the samples are not commercially available and therefore, genistin and genistein were chosen as external standards. Tectorigenin used in the recovery experiments was isolated and purified in our laboratory.